Department of Cell Biology, Institute for Biochemistry and Biology, University of Potsdam, 14469 Potsdam-Golm, Germany.
Mol Biol Cell. 2012 Jan;23(2):360-70. doi: 10.1091/mbc.E11-07-0595. Epub 2011 Nov 16.
Lamins build the nuclear lamina and are required for chromatin organization, gene expression, cell cycle progression, and mechanical stabilization. Despite these universal functions, lamins have so far been found only in metazoans. We have identified protein NE81 in Dictyostelium, which has properties that justify its denomination as a lamin-like protein in a lower eukaryote. This is based on its primary structure, subcellular localization, and regulation during mitosis, and its requirement of the C-terminal CaaX box as a posttranslational processing signal for proper localization. Our knockout and overexpression mutants revealed an important role for NE81 in nuclear integrity, chromatin organization, and mechanical stability of cells. All our results are in agreement with a role for NE81 in formation of a nuclear lamina. This function is corroborated by localization of Dictyostelium NE81 at the nuclear envelope in human cells. The discovery of a lamin-like protein in a unicellular organism is not only intriguing in light of evolution, it may also provide a simple experimental platform for studies of the molecular basis of laminopathies.
核纤层蛋白构成核纤层，对于染色质组织、基因表达、细胞周期进程和机械稳定性是必需的。尽管具有这些普遍功能，但迄今为止仅在后生动物中发现了核纤层蛋白。我们在粘菌中鉴定到了蛋白 NE81，其具有作为低等真核生物中的核纤层样蛋白的特性。这是基于其一级结构、亚细胞定位以及有丝分裂期间的调控，以及其 C 末端 CaaX 框作为正确定位的翻译后加工信号的要求。我们的敲除和过表达突变体揭示了 NE81 在核完整性、染色质组织和细胞机械稳定性方面的重要作用。我们所有的结果都与 NE81 在核纤层形成中的作用一致。这一功能得到了在人类细胞中粘菌 NE81 定位于核膜的结果的证实。在单细胞生物中发现核纤层样蛋白不仅在进化方面很有趣，它也可能为研究核纤层病的分子基础提供一个简单的实验平台。
